PEALE.] SOURCE OF WATERY OUTFLOW OF SPRINGS. 357 



Vitruvius believed that springs were due to an accumulation in subter- 

 ranean reservoirs of rain and melted snow. Descartes imagined that 

 the source of the water was the sea, from which water flowed into sub- 

 terranean caverns, was vaporized and afterwards condensed, finally es- 

 caping to the surface through crevices in the rocks. Mariotte and 

 Hallcy independently demonstrated that the fall of water in the form 

 of snow, rain, and dew is sufficient to account for all the water of rivers 

 and springs.* There may also be some truth in the idea of Descartes, 

 and certain springs may be due to communication with the ocean. 



That rain water does penetrate to considerable depths and supplies 

 springs is proved by the fact of the constant presence in mines, of water 

 that comes from above the galleries and drips from their roofs. In 

 Misnia, in Saxony, it has been known to form in drops on the roof of a 

 mine l,600feet deep,t and it is well known that after prolonged droughts 

 numerous springs become weak and many cease to flow, but are revived 

 after heavy rains.f It is a fact also that where springs exist there is 

 usually higher ground somewhere in the neighborhood, from which the 

 water may and probably does flow.§ 



In some places water may be forced to the surface by gases, and in 

 very hot springs no doubt the steam generated by the contact of the 

 water with the heated rocks below is a potent agency in forcing water 

 to the surface, but it is a well ascertained fact that the waters of springs 

 are meteoric in their origin. 



OUTFLOW OF SPRINGS. 



l^one of the springs or geysers in the Yellowstone ^National Park have 

 been gauged so that we have no exact data as to the amount of water 

 flowing from them. In the case of the geysers the flow is usually only 

 during the period of activity,|| and in the case of most of the ordinary 

 springs of the Park the overflow is probably less than would be expected. 



This will, however, have to be a subject of future investigation. It 

 will be interesting, however, to note the amount of water poured out by 

 well known springs that have been gauged. Le Coq says a million of 

 litres (200,000 gallons) is no unusual quantity of water to be poured 

 from a spring, and he says that of 500 springs in Central Prance, 231 

 have been gauged and yield 2,628,000 gallons every twenty-four hours. 



* Butfton also demonstrated it by selecting a lake without any outlet and showing 

 that the evaporation from its surface was equal to all the water that flowed into it. 

 {See pac/e 51 of Physical Geography^ by A. Bariington.) 



t/6id,page 44. 



t During the very dry season in August and September, 1881. the anthracite coal 

 mines in Schuylkill County, Pennsylvania, had to depend largely upon the supjily of 

 water found in the mines. 



^ It is interesting in this connection to compare the elevation of Yellowstone Lake 

 in the National Park with the two gevser areas of Fire Hole River: 



Feet. 



Yellowstone Lake has an elevation of 7, 738 



The Lower Geyser Basin has an elevation of 7, 230 



The Upper Geyser Basin has an elevation of 7, 372 



The geyser basins are also in valleys with high plateaus surrounding, which is the 

 case also with the other areas of the park, as tlie Shoshone Basin, Heart Lake Basin, 

 Haj'deu's Valley Springs, &c., while the lake has a high mountain range on the east 

 side and a high plateau on the west. 



II According to Mr. C. II. Wyman the eruptions of the " Excelsior Geyser" double 

 the volume of the Fire Hole Kiver, which, at this point, is 2 or 3 feet deep and nearly 

 lot) yards wide, and render it too hot to ford for a long distance. {Report of P. W, 

 Isorrib, auperiutendvni Yellowstone National Park, 1881, 2>. 55.) 



